Shutdown not completing cleanly on Ubuntu 22.04

I recently did a clean install of Ubuntu 22.04 on my 2008 MacBook 4.1 and then installed the old Ubuntu Unity desktop. (I actually like Unity and am prepared to take the performance hit compared to a lighter desktop.)

OS: Ubuntu 22.04.2 LTS x86_64
Host: MacBook4,1 1.0
Kernel: 5.19.0-41-generic
Uptime: 18 mins
Packages: 2138 (dpkg), 10 (flatpak),
Shell: bash 5.1.16
Resolution: 1280x800
DE: Unity 7.6.0
WM: Compiz
WM Theme: Yaru-dark
Theme: Yaru-dark [GTK2/3]
Icons: ubuntu-mono-dark [GTK2/3]
Terminal: gnome-terminal
CPU: Intel Core 2 Duo T8300 (2) @ 2.4 GHz
GPU: Intel Mobile GM965/GL960
Memory: 1579MiB / 3903MiB


Everything works great except that when I shut it down, the shutdown doesn't complete. This issue also happens with the standard desktop.
If I choose verbose shutdown so I can see what is going on, the process completes without error and the screen goes black but the fans remain running and the white light on the front illuminates if I close the lid. I have to then hard shutdown by holding the power button down for 5s.


Does anyone have any tips to force a complete shutdown on this hardware? Just in case its relevant, reboot works